Stabilized lubricant composition



Patented Feb. 20, 1945 2,370,080 STABILIZED LUBRICANT COMPOSITIONWilliam Schreiber, Philadelphia, Pa., aleignor to.

The Atlantic Refining Company, Phiiadelp Pa., a corporation ofPennsylvania No Drawing. ApplieationFebruary 3, 1943,

Serial No. 474,615

6 Claims.

The present invention relates to lubricating compositions, and moreparticularly to lubricating oils containing metal salts or soaps asdetergents, oxidation inhibitors,

form a haze in the oil in the presence of moisture.

An object of this invention is to prevent the formation of haze in ,oilscontaining metal salts or soaps, and especially in oils containing metalsalts of acid esters of acids of phosphorus.

A further object of this invention is the use of phosphatldes ormixtures of the same to pre vent the formation of haze in lubricatingoils containing metal salts, and particularly the alkaline earth metalsalts of acid esters of the thio-acids of phosphorus.-

It has been proposed heretofore to add to lubricating oils various metalsalts or soaps to function as detergents, antioxidants or anti-corrosionagents, and it has been found that the alkaline earth metal salts, andparticularly the barium salts of the acid esters of the acids ofphosphorus were highly efiective in this capacity, the only disadvantagebeing that these compounds tended to form a haze in thevoil in thepresence of moisture.

I have discovered that the formation of haze in oils containing a metalsalt of an acid ester of an acid of phosphorus may be reduced orprevented by the addition to the oil of a relatively small quantity of aphosphatide such as lecithin or cephalin. The-phosphatides belong to theclass of compounds having the general formula wherein R and R aresimilar or dissimilar fatty acid radicals, such as those derived fromstearic, palmitic, or oleic acids, and where X represents an aminoalcohol group. In the case of lecithin, X or the amino alcohol group ischoline T --CH2CH2N(CH3) :OH

and in the case of cephalin x is 'colamine anti-corrosion agents and thelike, which compounds tend to phorus, whereby a hydrated compound isformed which is less soluble in the oil than the original compound. Theaction of the phosphatide or lecithin in reducing or preventing theformationof haze is at present unknown.

In accordance with my invention, I incorporate in a hydrocarbon oil,such as a lubricating oil of suitable viscosity, a detergent orinhibitor comprising a metal salt of an acid ester of an acid ofphosphorus and a phosphatide, such as lecithin, in an amount suflicientto prevent the formation of. hazedue to the effect of moisture upon thesoap contained in the oil. The detergents, or inhibitors may be employedin various quantities depending upon thetype of oil used and the serviceto which the oil is to be put. For ordinary service in internalcombustion engines of passenger cars, light trucks, and the like,quantities of inhibitor of the order 012 0.01 per cent to about l percent by weight have been found satisfactory. On the other hand, forheavy duty service in Diesel engines, tractor engines, and heavy truckor bus engines, considerably more inhibitor is'required, i. e., amountsof the order of 1 per cent to 5 per cent, and in many cases between 5per cent and 10 per cent. The quantity of phosphatide required to reduceor prevent the formation of haze will vary depending upon thecomposition or nature of the inhibitor and the amount of such inhibitorincorporated in the oil. In general, the quantity of phosphatiderequired will range from about 10 per cent to per cent of the quantityof the inhibitor added to the oil.

The inhibitors which are employed in accordance with this invention inconjunction with the phosphatide comprise one or a mixture of two ormore metal salts of acid esters of an acid of phosphorus, andparticularly the alkt line earth metal salts of acid esters of athin-acid of phosphorus. The metals may be exemplified by Ca,

Ba,'Sr, Mg, Na, K, Li, Cu, Zn, Pb, Sn, Ni, Co and" hydroaryi groups maybe exemplified by phenyl, naphthyl, anthryl, cresyl, tolyl, xylyl,cyclohexyl, and naphthenyl. The mixed groups comprise propyl phenyl,butyl phenyl, amyl phenyl, hexyl naphthyl, cetyl cresyl, lauryl xylyl,as well as the mixed alkyl functions ethyl propyl, ethyl butyl, butylhexyl, hexyl lauryl, and the like.

Specific examples of the metal salts of the acid esters of the acids ofphosphorus are given in the following table.

Aluminum salt or lauryl cresyl acid ester of phosphoric acid Calciumsalt of phenyl stearyl acid ester oi phosphoric acid.

The metal salts of the acid esters of the acids of phosphorus may beused in conjunction with a phosphatide, or may be used in admixture withother inhibitors or detergents such as metal sulionates, metal salts ofphenol or phenol sulfides,

metal stearates, metal naphthenates or the like,

in conjunction with a phosphatide.

My invention may be further illustrated by I the following examples,which, however, are not to be construed as limiting the scope thereof.In these examples, samples of motor lubricating oil containing a metalsalt of an acid ester an acid of phosphorus, as well as samples oi theoil containing the metal salt and in addition various amounts oflecithin, were in one case subjected to storage under normal conditions,and in the second case, were contacted with a minute amount or addedwater (1 drop of water per 100 cc. of oil sample), and then stored. Thesamples were examined periodically to determine the length of timebefore haze appeared in the oil. The results are shown in the followingtable.

Days storage before haze formation Oil composition Normal stor- Incontact age with water 0ii+0.5% Ba salt of lauryl hexyl acidthiophosphate Less than 1 Less than i 0ii+0.5% Ba salt oi lauryl hexylacid thiophosphate+0.25% lecithin 21+ l6+ Oil-+0.59}, Ba suit oi laurylhexyl acid thiophoephate+0.t% lecithin 23+ Oil-wh z, Ba salt'oi dihexylacid thichosp ate Less than i Less than i O 1+0.5% Ba salt oi dihexyiacid thicphosp ate-i-O.5% lecithin. 24+ 16+ ()il+0.57 Zn salt of laurylhexyl acid thloph sphate 7 Less than 1 Oil+0.5% Zn salt of lauryl hexylacid thiophosphate+0.25% lecithin 26+ 17+ (NH-0.5% Zn salt oi leurylhcxyl acid thiophosphate+0.5% lecithin 29+ KH- The effect of lecithinupon lubricating oils containing a metal salt of an acid ester of anacid 01' phosphorus, when such oils are subjected to oxidation is shownin the following table. The oxidation test comprised heating cc. of theoil sample. to which had been added 0.1% oi iron naphthenate as anoxidation catalyst, at a temperature of 340 F. for 18 hours, whilebubbling air through the sample at a rate oi 300 cc. per minute. At thecompletion oi the heating period, the neutralization number of thesample was determined by conventional methods. In the table, inhibitor Ais a barium salt of lauryl hexyl acid thiophosphate and barium phenolsulfide, and inhibitor B is a barium salt of lauryl mixed hexyl acidthiophosphate and barium phenol sulfide.

Oil composition Neut. lv'o.

motor oil motor oil+0.25 0 inhibitor A motor oil+0.5 inhibitor A 30motor oil .25 0 inhibitor A-i-0.25% lecithin. 30 motor oil 0.25%inhibitor A+0.5% lecithin. 30 motor oil+0.5% inhibitor .+0.25% lecithin.30 motor 0ll+0.5% inhibitor A+0.6% lecithin.

. 30 motor oil-+0.25% inhibitor B 30 motor oll+0.5% inhibitor B 30 motoroll+0.25% inhibitor B+o.25% lecithin. 30 motor oil+0.25% inhibitor B+0.6lecithin. 30 motor oil+0.6% inhibitor R+0.257 lecithin" 30 motoroil-+0.15% inhibitor B+0.5%leclthln.

It will be apparent from the results given here-- inabove that lecithinexerts a beneficial influence upon oils containing metal salts of acidesters of acids of phosphorus not only from the standpoint of preventingthe formation of haze but also of decreasing the formation of acidity inthe oils due to oxidation.

Furthermore, while the combination 01 these metal salts and lecithin isparticularly adapted for use in connection with lubricants for internalcombustion engines t maintain general engine cleanliness, suchcombination of compounds is also .0! utility in oils for cutting orshaping metals, in greases and gear lubricants, and in other compositions wherein stability against oxidation is of prime importance.

1 claim:

1. A lubricant comprising hydrocarbon oil con taining a metal salt of anacid ester of an acid of phosphorus, said salt being present in anamountwhich would normally result in the formation of a haze in said oilin the presence oi moisture, and a phosphatide in an amount sumcient toRimm ng prevent said haze.

2. A lubricant comprising hydracaroon oil containing an alkaline earthmetal salt or an acid ester or an acid of phosphorus, said salt beinr;present in an amount which would normally result in the formation of ahaze in said oil in the presence of moisture, and a phosphatide in anamount suilicient to prevent said haze.

3. A lubricant comprising hydrocarbon oil containing an alkaline earthmetal salt of an acid ester of a thio-acid of phosphorus, said saltbeing present in an amount which would normally result in the formationof a haze in said 011 in the presence of moisture, and a phosphatide inan amount sumcient to prevent said haze.

4. A lubricant comprising hydrocarbon oil containing a barium salt of anacid ester of a table-- acid of phosphorus, said salt being present inan amount which would normally result in the tormation or a haze in saidoil in the presence of moisture, and a phosphatide in an amount sumcientto prevent said base.

5. A lubricant comprising hydrocarbon oil containing a barium salt of ahexyl lauryl acid ester taining 29. barium vszelt of a. dihexyl acidester of of thiophosphorlc acid in an amount which would thiophosphoricacid in an amount which would normally result in the formation of a hazeinsald normally result in the formation of a. haze in oil in thepresence of moisture, and lecithin in said oil in the presence ofmoisture, and lecithin 6 an amount suflicient to prevent said haze. inan amount sufiicient to prevent said haze. I v

6. A lubricant comprising hydrocarbon oil con- WILLIAM BCHREIBER.

